The field of this invention relates to a tightening apparatus and more particularly to a shaft tightening apparatus for a vise in which the same tightening force can be applied to a workpiece contained within the vise each time the shaft is tightened.
A machine tool is a power driven machine for shaping metal by a series of repeated cuts. A typical machine tool is a shaper, planer, milling machine, lathe, jig bore, drillpress, automatic screw machine, etc. Each one of these machines has a workpiece supporting surface. The workpiece supporting surface includes a vise within which is to be located the workpiece which is fixedly mounted within the vise. Tightening of the vise occurs through the use of a screw assembly which is manually turned to move movable jaws relative to fixed jaws. This vise has a pair of movable jaws so as to clamp the workpiece tightly in both the "X" and the "Y" directions.
Some types of machine tools are capable of performing machining operations with a high degree of accuracy. At the present time it is not uncommon to grind a surface of a workpiece to one hundred thousandths of an inch. It is common to manufacture a plurality of the parts that are being made. Accuracy of construction of each part is of the utmost importance.
The typical procedure for mounting a workpiece into the vise of a machine tool is to manually apply a desired level of torque through a handle assembly to the movable jaws of the vise to secure the workpiece in place. However, when working with a high degree of accuracy, even if the workpiece is solid metal, that unless each workpiece is clamped at precisely the same degree of force, there will be a slight bowing of one workpiece with respect to another which will cause the plurality of reproduced parts to not be exactly the same.
There is a need to construct a tightening device for movable jaws of a vise of a machine tool so that the jaws can be tightened to an exact level of tightening force each and every time it is tightened.